Since you asked, this is the system as of today....
- Khorn bass horns run wide open
- BMS 4590 coaxial compression drivers on Yuichi Arai 290Hz hypex radial flares.

I use the T2a transformer from the original Klipsch AA xover to set levels between the basshorn and the mid/high driver.

I also have a set of 150Hz trax midbasses with EVM12Ls that I used for a while, but they sounded out of place between the other two flares, with the setup I have now, sounding more of-a-whole.

Under construction are a set of LABhorn basshorns, and round 80Hx hypex midbasses with EVM15L drivers, and 270Hz Trax flares for the BMS. The LABs will be driven from a big ol' Perreaux SS amp and EQd flat, with the rest from one of my tubeamps.

The transformers used in the ALK xovers are model 3619 made by Universal in Texas. When my system is complete, I'll sell the Khorns (very sadly) as I just don't have the room to store them, so I'll buy a pair of the 3619's.

Al's crossovers bring some fairly strong reactions. On the Klipsch board most people seem to like them, but my experience with passive xovers with horns has not been good. Horns are most reactive at the edge and outside of their passbands, and adding a complex xover makes things worse IME. I'd rather keep it simple 6dB, and let the horms roll off on their own, they are BPFs by nature after all. My new midbasses are designed to complement the mid/high so there will likely be no LPF.
I haven't built the ALK's as the parts are quite expensive to import, and it's cheaper for me to build some more amps and go active as I have the parts on hand. I'd prefer not to though, because they take up too much space in my room.

Cheers

Note: this is a pic from Yuichi's page. My woodworking abilities are not that good. Mine are from 6 layers of 30mm mdf and a ton of resin. They weigh about 25kg + driver, and are 650mm x 400mm x 300mm (wdh)

Mr. Yuichi...... yes, I do know his work; just did not make the mental connection. I've seen his speaker work, over the years in MJ magazine; and his photography in a studio in Old Scottsdale, Arizona.

Never heard before of a transformer to set levels between drivers. Could you give a breif explanation?

Sure, they're simply a small trancsformer with a number of taps that allow you to adjust the levels by selecting a different ratio. the steps on the Klipsch tranny are a little coarse at around 3dB, but the 3619 will let you do some to about 1.5dB. The mid and high horns where I use them are much more sensitive than the rest of the system (114dB/1W/1m) so they're used to attenuate, with the added advantage (for tube amps esp) that the load on the amp decreases, ie increases resistance, the more you attenuate. I forgot to mention in the response to CG above, that one of the local winders has said he can produce some transformers for this application in 1/2dB steps, but at a larger cost.

Tannoy (and Klipsch of course, my Khorns are 74's) have done this for decades with the autoformers in their larger drivers, and IIRC even use the same technique to set the tweeter levels in the Mercury range (1dB steps) to allow for different sensitivities that different drivers have due to manufacturing tolerances.

Sure, they're simply a small trancsformer with a number of taps that allow you to adjust the levels by selecting a different ratio.
Cheers

Simple and nice idea I may try this in the future for my FE164 that needs about 6dB of attenuation with some M6 lamination instead of padding down with resistors. But in the other hand I have power to spare from an A4 so it could be a wast of time if there is no other advantage.

Under construction are a set of LABhorn basshorns, and round 80Hx hypex midbasses with EVM15L drivers, and 270Hz Trax flares for the BMS. The LABs will be driven from a big ol' Perreaux SS amp and EQd flat, with the rest from one of my tubeamps.

How are you constructing the round midbass horns? Wood? Concrete?
I would love some pics of your setup, including amps , if you have them.

Thinking about square Le Cleach' mid horns myself, 200-1000 Hz ,
round would of course be better but also a lot more work....

Nothing like dragging a thread back from the dead - I'm hoping it catches Brett's eye.

I'm considering the BMS 4590 as the basis for my speakers, either as 2 parts of a 3-way unity-style horn, or possibly just in a conventional CD flare mated to a 15 (lke in the Pi 7 corner units).

Brett - are you still high on the 4590? Any take on what is the lowest reasonable xover for domestic use where I'll be surprised if I ever put more than 1 watt into it?. I'm hoping I can make 400, as that is probably where the lower mid drivers in my Unity modelling would taper out.